Inside Unmanned Systems

AUG-SEP 2018

Inside Unmanned Systems provides actionable business intelligence to decision-makers and influencers operating within the global UAS community. Features include analysis of key technologies, policy/regulatory developments and new product design.

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AIR HAZARD TRACKING
50 August/September 2018 unmanned systems
inside
DRONES AND EPRI
EPRI sees the value in using drones for a variety of
applications in nuclear facilities, including radiation
monitoring and detection as well as asset inspection.
hazmat suits and walk into potentially danger-
ous situations.
While they can't talk about specific use cas-
es, the systems are typically deployed to survey
fixed points and determine if radioactivity at
those points has changed, said Bob Goldstein,
CEO of US Nuclear Corp. Such surveys are
completed about four times a year. Customers
are also interested in quantifying radioactive
plumes, determining where they're coming
from and where they're going. Another poten-
tial use is to check for gases coming out of the
stacks at these facilities.
"Right now the radioactivity levels in those
plumes is determined by computer simulation.
There's no measurement done," Goldstein said.
"You can take the drones up the stacks and
physically locate the plume and evaluate the
activity in the plum and which way it's going
to go, which is a great advance from what they
currently do. Now workers hold a detector at
waist level and point it up in the sky, hoping
to see the radiation in the plume. This new
method is going to work better."
Because there isn't a central spent fuel
repository in the U.S., plants are required to
store spent fuel on-site in dry cask storage con-
tainers located on independent spent fuel stor-
age installation (ISFSI) areas, Cinson said. The
UAS AND VIBRION
THE ELECTRIC POWER RESEARCH INSTITUTE (EPRI) AND CHARLOTTE
UAV are working on another drone project that involves vibration
imaging for indoor inspections of welds and other vibration sensitive
assets.
This visual based (non-contact) methodology allows for detection and
assessment of component and system vibration during operation, said
Tony Cinson, EPRI's senior technical leader—nuclear plant support. The
principle of operation of the OptiVibe (by Allied Reliability Group) is
to use high speed video to acquire data on systems/components and
compare frame by frame and pixel by pixel to detect and quantify cyclic
motion.
The system's output is essentially a vibrogram that renders an
image of the system with false coloring overlaid to signify regions of
vibration detected, he said. Further analysis quantitatively results in
an assessment of the frequency of vibration detected. This is similar
to outfitting the component with thousands of accelerometers (one
at every pixel within the image) to build a comprehensive view of the
system's motion.
"In relation to power plants, there are a number of pumps, valves, motors,
bearings and small bore cantilevered piping systems that typically
vibrate during use," he said. "This inspection methodology can provide a
precursor assessment to degradation before it becomes a significant issue
requiring immediate attention. For example, if a small bore piping system
is vibrating at a certain location, the location can be readily identified and
restraints can be installed to minimize future vibrations that could induce
mechanical fatigue cracking in a socket weld."
This is typically done with a tripod mounted system that's connected to
a laptop. Working with Charlotte UAV, Cinson and his team were able to
put the system onboard a customized UAS platform. For this to happen,
the drone had to be large enough to support the payload, which
includes a high speed camera, cinematography gimbal, an on board
NUC computer, and wireless data transmission equipment.
The cinematography gimbal provided the necessary vibration isolation
from the drone operation so high-quality data could be acquired. Flying
a small modular computer, it was essential that the OptiVibe acquisition
program could be executed and the large data files stored locally.
Wireless communication was a key functional requirement, making it
possible for the data to be acquired remotely and transferred without
contact.
"The concept here was to develop a mobile vibration imaging platform
that could remotely acquire data while either perched at a vantage point
of the system, or, ideally, acquire data while in hover mode targeting
the component of interest," Cinson said. "As of today, the system is
fully functional to acquire data from a perched vantage point as field
trials identified we still have too much motion (drift) of the UAV in hover
mode. The next phase plans to address this limitation by improving
balance, improving the UAV platform, and enhancing stable flight
controls. This includes making the necessary modifications to enable
stable flight in GPS denied environments."
Photo courtesy of EPRI.